EAGER: Scanning Ultrasound Probe for Semiconductor Sub-Surface Metrology

非技术：迫切需要在表面以下的纳米尺度上对半导体器件进行成像。这将使识别埋藏缺陷并在二维和三维结构（如微机电系统（MEMS））中进行失效分析成为可能。目前的纳米级地下成像技术需要大量的样品制备，速度非常慢，并且需要昂贵的设备。或者它们根本无法对不透明的样品成像。该解决方案是一种以合理的成本提供非破坏性，高通量纳米级埋藏缺陷成像的工具。该项目将结合扫描探针显微镜和超声全息术，以纳米级分辨率在三维空间揭示和表征地下特征。在这项技术中，一个悬臂监测沿着表面传播的声波。对这些波的振幅和相位的扰动携带着地表以下和地表附近结构的信息。这些变化被检测为频率和相位的微小差异，从而产生由悬臂检测到的节拍。当悬臂扫描表面时，这些变化被用来创建由地下和近地表特征和缺陷生成的空间映射。最终目标是将扫描探针显微镜硬件与功能电子集成到现场可编程门阵列，可配置集成电路中。该项目有望为半导体器件和结构的非破坏性成像开辟新的前景。一旦开发出来，这项技术将提供给其他机构，扩大用户基础，包括物理科学、工程和相关领域。项目负责人将把该项目的成果整合到本科课程中，并强调工程和物理科学原理如何影响材料和器件研究。通过“芝加哥科学”项目对小学进行课堂访问，将促进弱势群体的积极参与。技术方面：半导体行业迫切需要创新的成像模式。这对于识别埋藏缺陷和分层以及提供二维和三维结构的失效分析尤其需要。这些包括基于微机电系统（MEMS）和互连的设备。该项目将开发用于亚表面检测和失效分析的“扫描厚度共振声学显微镜”。目前的纳米级地下成像技术无法探测光学不透明的样品，或者需要大量和耗时的样品制备，速度非常慢，并且需要昂贵的计量设备。该解决方案是一种工具，可以提供非破坏性，高通量的纳米级埋藏缺陷成像，并且可以以合理的成本在研发周期的多个点上广泛部署。预期的应用将在半导体、MEMS和低k介电材料中识别二维和三维几何形状的埋藏纳米结构。这项创新技术将带来革命性的研究，以识别失效分析和埋藏缺陷，无论是在复杂的三维器件和纳米尺度分辨率的结构几何中的二维和三维材料堆栈。在这项技术中，悬臂监测表面声波的扰动，特别是它们的相位，由于它们各自的粘弹性特性的差异，这些相位携带着嵌入或掩埋的子结构的信息，这些信息反映在试样声波的散射中。由于亚表面纳米结构/缺陷的存在，体波的振幅和相位的变化以及近表面的变化影响了悬臂梁检测的差频信号（拍）的振幅和相位。这些变化用于创建由地下和近地表特征/缺陷生成的空间映射。为了实现这些努力，需要一种方法将扫描探针显微镜硬件，功能电子器件及其集成到现场可编程门阵列中，以同时产生和检测多重谐波。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical:There is an acute need to image semiconductor devices at nanometer scales below the surface. This will make it possible to identify buried defects and perform failure analysis in two- and three-dimensional structures such as micro-electromechanical systems (MEMS). Current nanoscale subsurface imaging techniques require extensive sample preparation, are exceptionally slow, and require expensive equipment. Or they are simply unable to image opaque samples. The solution is a tool which provides non-destructive, high throughput nanoscale imaging of buried defects at a reasonable cost. This project will combine scanning probe microscopy with ultrasound holography to reveal and characterize subsurface features with nanoscale resolution in three dimensions. In this technology, a cantilever monitors acoustic waves that travel along the surface. Perturbations to the amplitude and phase of these waves carry information about structures beneath and near the surface. These variations are detected as small differences in frequency and phase, resulting in beats that are detected by the cantilever. These variations are then used to create spatial mappings generated by subsurface and near-surface features and defects as the cantilever scans across the surface. The ultimate aim is to integrate scanning probe microscopy hardware with functional electronics into field-programmable gate arrays, configurable integrated circuits. The project promises to open new vistas in non-destructive imaging of semiconductor devices and structures. Once developed, the technology will be made available to other institutions, broadening the user base to include physical sciences, engineering and related fields. The PI will integrate results from this project into undergraduate courses and highlight how the principles of engineering and physical science impact materials and device research. Active participation of underrepresented groups will be promoted through classroom visits to elementary schools through the Science Chicago program.Technical:There is an acute and timely need for innovative imaging modalities in semiconductor industries. These are especially needed to identify the buried defects and delamination and provide failure analysis in both two- and three-dimensional structures. These include devices based on micro-electromechanical systems (MEMS) and interconnects. This project will develop "Scanning Thickness Resonance Acoustic Microscopy" for sub-surface inspection and failure analysis. Current nanoscale subsurface imaging techniques are unable to probe optically opaque samples or require extensive and time consuming sample preparation, are exceptionally slow, and require expensive metrology equipment. The solution is a tool which provides non-destructive, high throughput nanoscale imaging of buried defects, and that can be widely deployed at multiple points in the research and development cycle, at a reasonable cost. Anticipated applications will identify buried nanostructures in semiconductor, MEMS, and low-K dielectric materials both in 2D and 3D geometries. This innovative technology will bring transformative research in identifying the failure analysis and buried defects both in 2D and 3D materials stacks in complex three-dimensional devices and structural geometries with nanometer scale resolution. In this technology, the cantilever monitors the perturbation to the surface acoustic waves, especially their phase, which carry information about embedded or buried sub-structures reflected in the scattering of specimen acoustic waves due to the difference in their respective viscoelastic properties. Variations in the amplitude and phase of the bulk wave due to the presence of the sub-surface nanostructures/defects as well as the variations in near surface affect the amplitude and the phase of the difference frequency signal (beats) which is detected by cantilever. These variations are used to create spatial mappings generated by subsurface and near-surface features/defects. To realize these efforts requires a way to combine scanning probe microscopy hardware, functional electronics and its integration into field programmable gate arrays for simultaneous generation and detection of multiple harmonics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.